Nonlinear optical properties of Au/PVP composite thin films

Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530 nm due to the surface plasmon resonance of gold nanoparticles. Nonlinear optical properties are studied using standard Z-scan technique, and experimental results show large optical nonlinearities of the Au/PVP composite films. A large value of \chi^(3)/\alpha up to 0.56×10^-10esu\cdotcm is obtained, which is comparable to the best values reported in metal/oxide composite films.